Is Bosch off on its speed calculations?
- Thread starter rudym
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rudym
Active Member
@John from Connecticut - it would seem that ANY consumer as a RIGHT to truth in advertising. My pleasure is not at issue - the facts are at issue. I think responsibility rests with the maker of an item to properly list what something will or wont do...PERIOD. The public needs to hold corporations accountable.I agree with Rich C regarding non-military grade GPS. As for Bosch 'cheating us' on speed ( I own two Bosch Powered eBikes ) No Way : ) The
Bosch ebike motor portion of Bosch International is very tiny in their product line up, not even a blimp, so I don't see them 'wasting time etc'
fudging speed numbers....Lets say your computer is shutting down at 26 instead of 28. There's an up side to that, you'll experience longer ride
time because of slightly power drain from your battery at 26 mph
Lastly I also agree again with Rich C..." demand such extreme precision with a bicycle? After all it is supposed to be for pleasure." Great point,
getting out and riding an eBike is all about the fun, joy and freedom that eBiking offers. It's not a science project...Have fun
Bruce Arnold
Well-Known Member
Rudym, it seems you are determined to be upset about this.
The rest of us understand that there are variances in manufacturing. When they state a spec, it is within a given range. That range can be decreased but the extra cost to do so rises steeply. It can never be made to go away entirely. This is not lying. It's common knowledge that the specification is not exact.
Take ham radios, with which I'm very familiar. If a radio says it has 50 watts output, it might be as high as 60 or as low as 40. The user is not going to be able to tell the difference in performance if the output is 40 instead of 50. He can measure the difference with the right equipment but in practical usage, the radio will perform just as well except in very marginal conditions (which the operator may never experience.)
I have an amplifier that takes 1/2 watt from a handy-talky and boosts it. The specs say it has an output of 35 watts. I have a friend who installs radios for emergency services vehicles. He tested it and it came out to 27 watts. Roughly 20% off spec. But in actual usage, it performs brilliantly and has never let me down. It's range was as good as I had hoped when I bought it. I am able to hit a repeater over 70 miles away from my vehicle when conditions were good. I couldn't have asked for better with a 50 watt rig. The quality of the feed line and antenna, and how high up the antenna is, make much more of a difference than how many watts you can transmit with.
I can't see any practical impact of a bike doing 24 kph when it reads 26 kph. Stoplights and traffic conditions would make more of a difference in your overall time.
The rest of us understand that there are variances in manufacturing. When they state a spec, it is within a given range. That range can be decreased but the extra cost to do so rises steeply. It can never be made to go away entirely. This is not lying. It's common knowledge that the specification is not exact.
Take ham radios, with which I'm very familiar. If a radio says it has 50 watts output, it might be as high as 60 or as low as 40. The user is not going to be able to tell the difference in performance if the output is 40 instead of 50. He can measure the difference with the right equipment but in practical usage, the radio will perform just as well except in very marginal conditions (which the operator may never experience.)
I have an amplifier that takes 1/2 watt from a handy-talky and boosts it. The specs say it has an output of 35 watts. I have a friend who installs radios for emergency services vehicles. He tested it and it came out to 27 watts. Roughly 20% off spec. But in actual usage, it performs brilliantly and has never let me down. It's range was as good as I had hoped when I bought it. I am able to hit a repeater over 70 miles away from my vehicle when conditions were good. I couldn't have asked for better with a 50 watt rig. The quality of the feed line and antenna, and how high up the antenna is, make much more of a difference than how many watts you can transmit with.
I can't see any practical impact of a bike doing 24 kph when it reads 26 kph. Stoplights and traffic conditions would make more of a difference in your overall time.
rudym
Active Member
@Bruce Arnold - folks seem to misinterpret my intent. I am NOT upset. I, as a consumer demand truth in advertising. If Bosch would simply advertise the truth 26 mph cutout or 43 kph all good. Same for Trek. Why lie? Why overstate? Why manipulate the consumer?
Truth in advertising? We have a tv series in Australia called gruen ( http://www.abc.net.au/tv/programs/gruen/ )
Mr. Coffee
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I think people are confusing two different issues.
@rudym and @AlanDB are both reporting errors of 2.5+mph at 26mph, so an error on the order of ten percent of the indicated speed.
The thread @tompat referred to described an error of 2kph at 46kph, so an error on the order of four percent of the indicated speed.
My own experiments show the the speedometer is accurate to within three percent of indicated speed at speeds of up to 20mph (so 0.6mph at 20mph). It also seems like the Bosch system is rounding upwards very slightly but the effect is so subtle that I can't characterize it well.
With my bike (Bosch Intuvia, Bosch Performance CX) there is no way I can get a ten percent error on indicated speed, at least for speeds under 20mph.
As I said before, GPS is not sufficiently accurate to be used as a baseline for speed measurements. Also, it is difficult under a lot of conditions to ride at a very steady speed (so go try to ride your bike on the flats at exactly 9.0 mph for two miles and tell me how it goes). For me at least it is easiest to cycle at a steady speed on a moderate uphill.
Since your bike can vary in speed quite a bit and the Bosch system samples the speed at a fairly high rate you can also get errors using other systems which sample at a lower rate. If you are accelerating, even slightly (say you are riding downhill) the Bosch system will almost always display a slightly higher speed than a system (e.g. a radar gun or radar sign) that samples at a lower rate.
A three or four percent error as characterized is within the range that much (but not all) of it could be explained by tire inflation.
What I'm trying to communicate is that there are a lot of chopped vegetables in this bowl of salsa and you'll want to carefully characterize all of the possible errors that might occur before you make any serious accusations. I might be completely wrong in my observations and you might be one hundred percent right, But unless you are willing to be at least a little bit systematic (which so far I haven't seen) I can't really consider the claims of some kind of conspiracy at all credible.
@rudym and @AlanDB are both reporting errors of 2.5+mph at 26mph, so an error on the order of ten percent of the indicated speed.
The thread @tompat referred to described an error of 2kph at 46kph, so an error on the order of four percent of the indicated speed.
My own experiments show the the speedometer is accurate to within three percent of indicated speed at speeds of up to 20mph (so 0.6mph at 20mph). It also seems like the Bosch system is rounding upwards very slightly but the effect is so subtle that I can't characterize it well.
With my bike (Bosch Intuvia, Bosch Performance CX) there is no way I can get a ten percent error on indicated speed, at least for speeds under 20mph.
As I said before, GPS is not sufficiently accurate to be used as a baseline for speed measurements. Also, it is difficult under a lot of conditions to ride at a very steady speed (so go try to ride your bike on the flats at exactly 9.0 mph for two miles and tell me how it goes). For me at least it is easiest to cycle at a steady speed on a moderate uphill.
Since your bike can vary in speed quite a bit and the Bosch system samples the speed at a fairly high rate you can also get errors using other systems which sample at a lower rate. If you are accelerating, even slightly (say you are riding downhill) the Bosch system will almost always display a slightly higher speed than a system (e.g. a radar gun or radar sign) that samples at a lower rate.
A three or four percent error as characterized is within the range that much (but not all) of it could be explained by tire inflation.
What I'm trying to communicate is that there are a lot of chopped vegetables in this bowl of salsa and you'll want to carefully characterize all of the possible errors that might occur before you make any serious accusations. I might be completely wrong in my observations and you might be one hundred percent right, But unless you are willing to be at least a little bit systematic (which so far I haven't seen) I can't really consider the claims of some kind of conspiracy at all credible.
The discrepancy really doesn't upset me that much either, but I can see how it would make some folks angry. I seldom ride above 16 MPH or so, except on some downhill runs where the assist really doesn't matter much. What I have noticed with my Gazelle Arroyo is that the assist starts cutting out when the Intuvia shows 19 MPH, and the actual speed at that point (based on the GPS speedometer) is between 16.5 and 17 MPH. So my 20 MPH e-bike is really more like a 17MPH e-bike. Again, no big deal for me as I ride primarily for recreation and exercise, but I can see how many riders would be disappointed with it.
Bruce Arnold
Well-Known Member
Biffo1262
New Member
My Raleigh Motus with Bosch Purion display also reads the speed about 10% high but the odometer seems to be as accurate as my car, motorhome and GPS display. I have also doubled checked distance with the measurement tool on Google Earth on PC. Speed inaccuracy means absolutely nothing at all on a bicycle but the odometer does play a role in battery calculations. I just don't understand why, once you have calculated discrepancy, it should be a problem other than to anyone who has OCD tendencies and, having family members who are OCD 'sufferers', I can appreciate their frustration. They can't help it and nothing you can do will alter the fact that everything has to be perfect, as they see it. As for Bosch conspiracy theories, well, what do they gain. My ebike is UK spec which means assistance should cut out at 15.5mph, roughly 17mph indicated taking in the 10% discrepancy yet, it doesn't. Mine seems to be 'faulty', in that assistance seems to cease at about 22mph (indicated) 20mph actual. This seems to be in common with many other Motus owners so I fail to see, even with the high readings, what any form of conspiracy could be seen in this. The high assistance cut out isn't something I'm likely to complain about, same as others in the same situation. If the odometer is accurate, the motor assists to at least 15.5mph (actual), the speedometer is within the 10% high legal tolerance then where is the cause for complaint?
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My Stromers Speed/odometers have “seemed” optimistic since my 1st Sport model to my wife’s 2s. The S also can run over 28 so I believe I am getting the 28 mph but being told a little more. My St2 has slightly smaller tires than original, the same size as the S, speedometer is is off even more but I am not surprised. I have read I get 28.x per design , slightly over the 28 . None of my info is extremely accurate or scientific but after 7 years of Stromer I am fairly confident in the results.
Haha this thread is crazy...
Bosch (maybe others) have it set in firmware so that if you have tire circumference, tire pressure etc all perfect the bike will go a tiny bit slower than legal limit but are still displaying 20mph etc.
They don't want you to be going faster than than the legal limit or else the law will come down on them. And with a zillion motors in the world, it's just too risky to bump it up a little higher, even if there is actually a tolerance permitted by EU law, etc.
So bike companies take on the risk by trying to introduce a bit of an offset to bring it as close to legal limit as possible. Maybe they don't get it perfect of course, or they don't even bother to mess with the motor supplier defaults. But the dealer is able to adjust the circumference by +/5% and get you the 1-2mph that is missing. It's really that simple. German companies are very law-abiding
Bosch (maybe others) have it set in firmware so that if you have tire circumference, tire pressure etc all perfect the bike will go a tiny bit slower than legal limit but are still displaying 20mph etc.
They don't want you to be going faster than than the legal limit or else the law will come down on them. And with a zillion motors in the world, it's just too risky to bump it up a little higher, even if there is actually a tolerance permitted by EU law, etc.
So bike companies take on the risk by trying to introduce a bit of an offset to bring it as close to legal limit as possible. Maybe they don't get it perfect of course, or they don't even bother to mess with the motor supplier defaults. But the dealer is able to adjust the circumference by +/5% and get you the 1-2mph that is missing. It's really that simple. German companies are very law-abiding
Mid-drive manufacturers really don't like speed pedelecs. They understand that at higher speeds the gear ratio essentially makes the mid drive an inefficient system compared to a hub motor that applies torque directly at the rear wheel. This something that is just not understood by many consumers so they buy mid-drive eBike for fast Class 3 performance and are disappointed in the assist provided above 20mph and the feeling that the stated assist speed is a bit optimistic. Don't get me wrong, mid-drives are wonderful ebikes but their ideal place in the market is on offroad / mtn bikes where slower speed climbing performance is a priority (at the slower speeds the gear ratio can actually increase the torque from the crank to the rear wheel).
The Bosch system of spinning a smaller front chain ring is a reasonable way to improve performance at the higher speeds but my guess is the motor has to be wound such that the Kv is higher which could reduce the low speed performance of the motor somewhat. Anyway, I just think more urban mobility riders should spend more time considering the merits of geared and direct drive hub motors even though they tend to be a bit heavier than mid-drives and not as well marketed.
The Bosch system of spinning a smaller front chain ring is a reasonable way to improve performance at the higher speeds but my guess is the motor has to be wound such that the Kv is higher which could reduce the low speed performance of the motor somewhat. Anyway, I just think more urban mobility riders should spend more time considering the merits of geared and direct drive hub motors even though they tend to be a bit heavier than mid-drives and not as well marketed.
pedelecsva
New Member
I totally agree with you. I’ve bought a bike that is advertised to assist up to 45km/h, and I am only getting 42km/h. I use it to commute 47km each way to and from work, and the 3km/h does make a difference.
I have the Kiox and I initially put in the correct circumference for my tires. That resulted in 40 km/h true speed, and indicates 45. I then lowered the circumference to lowest possible, and now I get 42km/h indicated and true.
It is stupid that you can set a circumference down to millimeter accuracy, when it then indicates 10% error.
The motor is capable of helping much more than 45km/h, so the only reason for bosch to limit it to 43 km/h, would be to error on the safe side.
I wrote Bosch to address the issue, and they said that a Bosch service center should be able to fix this, but I have a strong feeling, they are just going to change the circumference. I don’t want it to indicate 45km/h, I want to travel at 45km/h.
That's a great ebike but do you really get adequate assist going thru the gear ratios for high speed cruising. If riding on a 44T front and an 11T rear onlly 1/4 of the motor + human torque reaches the rear wheel. This is one of the main issues with mid-drives and why most are not that helpful at higher speeds.
The math aside, what is "adequate assist"?
On flat terrain and no headwind I have no particular problems maintaining the top assist speed of my Speed Pedelec.
I'd say then it has "adequate assist".
Note, we are talking about electric assisted bikes. The very bottom line is you still need to put in your own effort to it. If you don't want that, there are electric mopeds that don't have pedals at all.
On flat terrain and no headwind I have no particular problems maintaining the top assist speed of my Speed Pedelec.
I'd say then it has "adequate assist".
Note, we are talking about electric assisted bikes. The very bottom line is you still need to put in your own effort to it. If you don't want that, there are electric mopeds that don't have pedals at all.
NorthWestRider
New Member
I'm in the same boat with my speedo being overly optimistic. I set my tire size as small as possible and it's still about 0.5mph fast. Did I do extensive testing? No. Do I care that much? Not really. My bike goes in for its complimentary 250mi tune up so I'll post back if they "fix" it. The shop is pretty confident that the Bosch will be more accurate than my satellite based GPS but said they would check it. My bike is a 2019 Raleigh Redux, class 3, Bosch speed motor, Purion display.
FlatSix911
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Bosch was indicted in the VW diesel-gate scandal for the emissions cheating software... just a coincidence with eBikes? I think not...
www.reuters.com
www.forbes.com
Bosch worked 'hand-in-glove' with VW in emissions fraud: lawyers
German auto supplier Robert Bosch GmbH was a "knowing and active participant" in a decade-long scheme by Volkswagen AG to evade U.S. emissions laws, according to lawyers for U.S. owners of polluting VW diesel vehicles.
www.reuters.com
German Parts Maker Bosch Gets Off With Relatively Light $100 Million Fine From VW Dieselgate
Robert Bosch GmbH didn't make headlines in VW Dieselgate -- though German prosecutors say the company played a key role in the scandal.
www.forbes.com
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Biffo1262
New Member
You have it one. If you want to ride around making no effort at all then ANY form of cycling is not for you. You need to be on a motorcycle forum. My Motus does exactly what it says on the tin. It ASSISTS me should I need assistance and even the ECO setting makes a considerable difference when cycling into a head wind. It's not about speed at all with this type of ebike it's about assisted effort.
As for the speedometer accuracy I have found, on my particular machine, that adjusting the position of the magnet on the wheel DOES have an effect on the readout. I moved the magnet nearer to the rim and that actually did reduce the rather optimistic speed reading though I'm not sure exactly why it does....not that I really care.
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rudymsmith
New Member
Tell that "law abiding" to VW.Haha this thread is crazy...
Bosch (maybe others) have it set in firmware so that if you have tire circumference, tire pressure etc all perfect the bike will go a tiny bit slower than legal limit but are still displaying 20mph etc.
They don't want you to be going faster than than the legal limit or else the law will come down on them. And with a zillion motors in the world, it's just too risky to bump it up a little higher, even if there is actually a tolerance permitted by EU law, etc.
So bike companies take on the risk by trying to introduce a bit of an offset to bring it as close to legal limit as possible. Maybe they don't get it perfect of course, or they don't even bother to mess with the motor supplier defaults. But the dealer is able to adjust the circumference by +/5% and get you the 1-2mph that is missing. It's really that simple. German companies are very law-abiding
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